Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Valuation of Company's Assets and Liabilities Measured at Fair Value

The following table summarizes the valuation of the Company’s assets and liabilities measured at fair value as categorized based on the hierarchy described in Note 2.

	Level 1		Level 2			Level 3		Total
	(In thousands)
As of September 30, 2017
Money market funds	$	25,213	$	—		$	—	$	25,213
Securities available-for-sale
Corporate debt		—		168,278			—		168,278
Trading securities
Corporate debt		—		65,885			—		65,885
Mutual funds held in rabbi trust		—		3,058			—		3,058
Foreign currency forward position		—		591			—		591
Total	$	25,213	$	237,812		$	—	$	263,025
As of December 31, 2016
Money market funds	$	58,573	$	—		$	—	$	58,573
Securities available-for-sale
Corporate debt		—		118,870			—		118,870
Trading securities
Corporate debt		—		74,207			—		74,207
Mutual funds held in rabbi trust		—		1,327			—		1,327
Foreign currency forward position		—		(266	)		—		(266	)
Total	$	58,573	$	194,138		$	—	$	252,711

Summary of Foreign Currency Forward Contracts

A summary of the Company’s foreign currency forward position is as follows:

	As of
	September 30, 2017		December 31, 2016
	(In thousands)
Notional value	$	89,035	$	66,972
Fair value of notional		88,444		67,238
Fair value of the asset (liability)	$	591	$	(266	)

Summary of Company's Investments

The following is a summary of the Company’s investments:

	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
	(In thousands)
As of September 30, 2017
Securities available-for-sale
Corporate debt	$	168,455	$	18	$	(195	)	$	168,278
Trading securities
Corporate debt		65,940		67		(122	)		65,885
Mutual funds held in rabbi trust		2,729		329		—			3,058
Total trading securities		68,669		396		(122	)		68,943
Total investments	$	237,124	$	414	$	(317	)	$	237,221
As of December 31, 2016
Securities available-for-sale
Corporate debt	$	119,073	$	13	$	(216	)	$	118,870
Trading securities
Corporate debt		74,394		47		(234	)		74,207
Mutual funds held in rabbi trust		1,212		115		—			1,327
Total trading securities		75,606		162		(234	)		75,534
Total investments	$	194,679	$	175	$	(450	)	$	194,404

Summary of Fair Value of Investments Based upon Contractual Maturities

The following table summarizes the fair value of the investments based upon the contractual maturities:

	As of
	September 30, 2017		December 31, 2016
	(In thousands)
Less than one year	$	133,207	$	117,904
Due in 1 - 5 years		104,014		76,500
Total	$	237,221	$	194,404

Fair Values and Unrealized Losses on Investments

The following table provides fair values and unrealized losses on investments and by the aging of the securities’ continuous unrealized loss position as of September 30, 2017 and December 31, 2016:

	Less than Twelve Months					Twelve Months or More					Total
	Estimated fair value		Gross unrealized losses			Estimated fair value		Gross unrealized losses			Estimated fair value		Gross unrealized losses
	(In thousands)
As of September 30, 2017
Corporate debt	$	173,000	$	(284	)	$	5,426	$	(33	)	$	178,426	$	(317	)
As of December 31, 2016
Corporate debt	$	136,667	$	(449	)	$	2,000	$	(1	)	$	138,667	$	(450	)